You have a requirement to host a web-based application with high availability. So you create an Elastic Load Balancer and place the Auto Scaling group behind the Elastic Load Balancer. You need to ensure that users only access the application via the DNS name of the load balancer instead of the EC2 public IP addresses. How would you design the network part of the application? Choose 2 answers from the options below.

Answer options:

A.Configure 2 public subnets for the Elastic Load Balancer
B.Configure 2 private subnets for the Elastic Load Balancer
C.Configure 2 public subnets for the Auto Scaling group
D.Configure 2 private subnets for the Auto Scaling group

Answer - A and D
The AWS Documentation mentions the following.
Use Case: A load balancer, two public subnets, two private subnets, two NAT Gateways,
The NAT Gateway goes into both public subnets (Public-Subnet-A, Public-Subnet-B).
The EC2 instances are launched in private subnets across two AZs (Private-Subnet-A, Private-Subnet-B).
The Route Table Private-Subnet-A points to the NAT Gateway in Public-Subnet-A.The Route Table Private-Subnet-B points to the NAT Gateway in Public-Subnet-B.If one of the AZs should fail, then the EC2 instances in the remaining private subnet will still communicate with the Internet because they have their own NAT Gateway in that AZ.
Option B is incorrect since the ELB needs to be placed in the public subnet to access the Internet.
Option C is incorrect because the Auto Scaling groups should be placed in the private subnets for security and the question also requires that users cannot access the application through the public IP addresses of the instances.
For more information on an example to use the Load balancer, please visit the below URL-
https://aws.amazon.com/premiumsupport/knowledge-center/public-load-balancer-private-ec2/